Fossils
In an undisturbed rock layer, where do you find the oldest layer?
At the bottom
A volcanic ash layer is found between two sedimentary rock layers containing fossils. How can scientists use both absolute and relative dating to determine the age of the fossils?
Scientists can use absolute dating (radiometric dating) to find the exact age of the volcanic ash layer. Then, they apply relative dating to determine that the fossils in the sedimentary layers above and below must be slightly younger or older than the ash layer. This helps refine the fossil’s age estimate.
The remains of an organism that were common and widespread but existed for only about 1 million years or less.
Index fossils
Whaat does the Law of Superposition state?
In undisturbed rock layers, the oldest layer is at the bottom and the youngest layer is at the top.
True or False: To determine the absolute date of an object you must compare one layer to another layer.
False
What type of organism parts are more likely to become a fossil?
Hard parts - like bone, teeth
The age of the largest mass extinction
The end of the Paleozoic Era
Which is younger, the top layer or a fault line?
The fault line
The age when oxygen first appeared in the atmosphere
Proterozoic Eon
The current geologic era we live in is called this.
Cenozoic Era
Fossils of these animals are more common because they lived in environments where sediment deposition happened frequently.
Water-dwelling organisms
What are the divisions in the geologic time scale based on?
Major events and changes in Earth’s history
The Paleozoic, Mesozoic, and Cenozoic Eras are divisions of this geologic time unit.
Phanerozoic Eon